The present invention relates to an endoscope.
In order to observe a human body cavity, a general endoscope has an object optical system and an imaging device. The object optical system and the imaging device are provided at a tip of an insertion tube of the endoscope. Generally, a charge-coupled device (hereinafter, referred to as a CCD) is used as the imaging device.
The endoscope must be sterilized every time the endoscope is used. Recently, an autoclaving method is widely use to sterilize the endoscope, since the autoclaving method is harmless to a human body and is capable of killing Helicobacter Pylori and viruses, etc. In the autoclaving method, a work is placed under a high-temperature (about 120.degree. C. to 130.degree. C.). However, since the CCD may break when heated more than 80.degree. C., it is difficult to sterilize an endoscope with the CCD by autoclaving method.
Further, since the pitch between pixels of the CCD is small (almost 6 .mu.m to 10 .mu.m), the CCD may break when an electric discharge occurs in case the static electricity is generated during the assembly of the endoscope. Also, the CCD may break due to an impact when the tip of the endoscope is hit against something. In such cases, the endoscope must be totally disassembled and reassembled in order to replace the CCD.
Furthermore, a recently developed endoscope has a hood at the tip of an insertion tube. The hood is provided for urging a surface of a human body cavity thereby to keep an appropriate distance between an object (a surface of the human body cavity) and an optical system (accommodated in the insertion tube). The hood is fixed to the insertion tube. Thus, in case of replacing the CCD or the optical system of the insertion tube, it is necessary to remove the hood beforehand. This makes the replacing operation complicated.